Compaq Deskpro 4000N - Desktop PC, Maintenance & Service Manual

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Compaq Deskpro 4000S and 4000N Personal Computers 4-1
chapter
4
R
EMOVAL AND
R
EPLACEMENT
P
RELIMINARIES
This chapter provides general service information for the computer. Adherence to the procedures and
precautions described in this chapter is essential for proper service.
CAUTION: When the computer is plugged into an AC power source there is always voltage applied to the
system board. You must disconnect the power cord from the power source before opening the computer to
prevent system board or component damage.
4.1 Electrostatic Discharge Information
A sudden discharge of static electricity from your finger or other conductor can destroy static-
sensitive devices or microcircuitry. Often the spark is neither felt nor heard, but damage occurs. An
electronic device exposed to electrostatic discharge (ESD) may not be affected at all and can work
perfectly throughout a normal cycle. The device may function normally for a while, then degrade in
the internal layers, reducing its life expectancy.
Networks built into many integrated circuits provide some protection, but in many cases, the
discharge contains enough power to alter device parameters or melt silicon junctions.